As known, EECs electronically control operation of gas turbine engines based on selected control algorithms executed by the EEC. The EEC applies the control algorithms in response to sensed engine parameter signals to provide electrical control signals to engine mounted electro-mechanical devices. These include linear and rotary position actuators which position various engine valves, vanes, etc. to regulate engine performance.
To ensure reliability, the EEC includes redundant control circuitry, i.e. primary and secondary control channels. The sensed engine parameter signals are also redundant, and are applied to each of the EEC channels. The sensed parameter signals include analog (amplitude and frequency) signal formats, as well as digital.
Digital electronic engine controls (DEEC) use digital signal processing to apply the control algorithms to the sensed parameter signals. For the analog sensed signal formats this requires analog-to-digital (A/D) conversion, all of which is well known. Since A/D conversion is sensitive to spurious noise associated with the analog signal it is also known to provide the DEEC with input selection logic. This logic selects the best signal from among the two actual sensed parameter signals.
The executed control law algorithms provide the output control signals, including actuator position command signals to the engine mounted actuators, which physically position the various valves and vanes in the engine. Since reliability of the actuator loops is critical to engine reliability, the redundant position feedback signals from the actuator are compared to detect gross malfunction. As a result, the DEEC can detect a faulty actuator control loop and use a backup actuator system (if available). The difficulty, however, is the ability to isolate the particular failed component in the actuator operating system, and then to identify the failed component to maintenance personnel.